Superantigens (SAG) are believed to contribute to the pathogenesis of certain infectious agents by activating a broad subset of primary T-cells. Through association with MHC class II molecules outside of the peptide recognition cleft, the SAG is able to bind and activate T-cells expressing a particular T-cell receptor (TCR) beta chain variable gene. Recent experiments have identified a SAG, encoded by the human endogenous retrovirus K18 env (HK18 env) gene, which is transcriptionally activated following infection with the Epstein-Barr virus (EBV). EBV is a ubiquitous, B-cell tropic herpesvirus, which has been identified as a causative agent for infectious mononucleosis (IM), a self-limiting lymphoproliferative disorder characterized by mononuclear leukocytosis. The association of EBV and a SAG activity provides an attractive hypothesis for the mechanism of EBV related T-cell proliferation. However, the exact role of the SAG in EBV infection and pathology is not currently known. The goal of this phase I application is to evaluate the role of the recently identified SAG molecule, HERV-K18 Env, in EBV infection and pathology. Our working hypothesis is that SAG activated T-cells supply an essential component necessary for the development of EBV associated B-cell lymphomas. Thus, blocking T-cell activation by the SAG could effectively prevent the development of EBV tumors. If this hypothesis is correct, these studies will provide a basis for phase II studies in primate models of EBV infection, in order to examine the potential for anti-SAG antibodies as preventative or therapeutic agents against EBV related disease.